Technical Field
This disclosure relates to a sheet feeder, an image forming apparatus incorporating the sheet feeder, and a method of removing discharge products in the image forming apparatus.
Related Art
Various types of sheet feeders are known to be included in an image forming apparatus. Such an image forming apparatus has a configuration in which an electrostatic sheet attraction and separation system generates an electric field on a charged target belt so that the charged target belt contacts an uppermost sheet that is placed on top of a bundle of sheets to attract and separate the uppermost sheet from the charged target belt.
A comparative sheet feeder having such an electrostatic sheet attraction and separation and separation system includes a dielectric belt that is a charged target member wound around two rollers, a charger that contacts the dielectric belt, and an electric charge applier that applies an alternating voltage to the charger to apply an alternating electric charge to the dielectric belt.
Prior to a sheet feeding operation, the dielectric belt is separated from the bundle of sheets. When the uppermost sheet is separated from the bundle of sheets to be fed from a sheet container or a sheet tray, the dielectric belt is rotated before being applied with an alternating electric charge via a charging blade. The alternating electric charge is uniformly applied to the dielectric belt, the rotation of the dielectric belt is stopped. Thereafter, the dielectric belt is moved toward the bundle of sheets. Then, the dielectric belt contacts the uppermost sheet of the bundle of sheets so that the uppermost sheet of the bundle of sheets is attracted to the dielectric belt.
When the uppermost sheet of the bundle of sheets is attracted to a surface of the dielectric belt that is placed on an upper face of the bundle of sheets, the dielectric belt is moved in a direction to separate from the bundle of sheets, so that the uppermost sheet attracted to the dielectric belt is separated from the bundle of sheets. When rotation of the dielectric belt starts, the uppermost sheet attracted to the dielectric belt is conveyed toward a pair of sheet conveying rollers that is a sheet holder.
Generally, proximity electrical discharge is generated between a charging member and the dielectric belt so as to apply an alternating electric charge to the dielectric belt. The proximity electrical discharge produces discharge products such as nitrogen oxide, and therefore the discharge products adhere to the dielectric belt. Then, as discharge products accumulates on the surface of the dielectric belt due to long use of the dielectric belt, the dielectric belt becomes more difficult to be charged, and therefore a sheet becomes more difficult to be electrostatically attracted to the dielectric belt.